This type of waste heat utilization apparatus is provided with a Rankine cycle having a circulation path for circulating a refrigerant as a working fluid. In the Rankine cycle, an evaporator for heating and evaporating the working fluid by making use of waste heat from the internal combustion engine, an expander for expanding the working fluid supplied thereto from the evaporator to generate rotary driving force, a driven unit to which the rotary driving force generated by the expander is transmitted, a condenser for condensing the working fluid supplied thereto from the expander, and a pump for delivering the working fluid supplied thereto from the condenser to the evaporator are sequentially inserted in the circulation path.
Waste heat from the internal combustion engine includes the heat of EGR (Exhaust Gas Recirculation) gas, which is part of the exhaust gas recirculated to the intake side for the purpose of reducing NOx, that is, the heat released from an EGR cooler arranged in an EGR passage to lower the temperature of the EGR gas. A Rankine cycle system utilizing the heat of the EGR gas has been known in the art (cf. Patent Document 1).